I think ZZP says 300HP for stock CV axles. They sell stage 2 axles that handle 9s passes all day long. There is a difference in axles for HD trans and non-HD though.
From ZZP: "All 97+ 3800 cars use the same driverside axle, however the passengerside axle can be different. Supercharged cars use a Heavy Duty “HD” passengerside axle and the non supercharged cars use a non HD axle. You can convert a non-HD car to a HD car by simply installing the supercharged differential, diff cover, and the passengerside axle which we offer, it is called the 4t65e HD upgrade kit. So someone with a non supercharged car that wants an OEM replacement axle would have to order a non-HD axle."
Hope this helps.